Simplify logic by setting default value for MESON_INSTALL_DESTDIR_PREFIX
diff --git a/build/meson/InstallSymlink.py b/build/meson/InstallSymlink.py
index d0f5151..3f2998c 100644
--- a/build/meson/InstallSymlink.py
+++ b/build/meson/InstallSymlink.py
@@ -45,11 +45,9 @@
   args = parser.parse_args()
 
   dir_mode = int(args.mode, 8)
-  install_dir = pathlib.Path(args.install_dir)
 
-  meson_destdir = os.environ.get('MESON_INSTALL_DESTDIR_PREFIX')
-  if meson_destdir:
-    install_dir = pathlib.Path(meson_destdir).joinpath(install_dir)
+  meson_destdir = os.environ.get('MESON_INSTALL_DESTDIR_PREFIX', default='')
+  install_dir = pathlib.Path(meson_destdir, args.install_dir)
   install_symlink(args.source, args.dest, install_dir, args.isdir, dir_mode)